The refraction layer/channel combines all kind of transparency and translucency effects.

You can make: Glass, Sandblasted Glass, Crystals, Fluids, SSS (Subsurface Scattering), Translucency and other materials. There is also a volume effect in it to make physical correct Glass and Fluids, the thicker/deeper a transparent object or fluid is, the less transparent it gets, the volume can get tinted in a color. Best is to use a very slight and light color of the one the object shall have, so for a dark red wine it might be enough to use a slight rose tined in the volume effect, the volume also uses an IOR for refraction.

Refraction Color

Color refraction color. Note that the actual refraction color depends on the reflection color as well.

Brightness– use this setting to adjust the brightness of a channel color.

Texture – here an image texture or shader can be defined.

Mix Mode – use these parameters to mix the color and texture panes using one of four modes. The default mode for all channels is Normal. If you load a texture or shader, it is placed on a layer above the color (i.e. the texture is placed on top of the color). Please consult the Cinema4d documentation about the different mix modes.

Mix Strength – defines the mixing proportion between the texture and color.

Refraction Layer Parameters

IOR – index of refraction for the material, which describes the way light bends when crossing the material surface. A value of 1.0 means the light will not change direction.

Texture – here an image texture or shader can be defined.

Cutoff – this is a threshold below which refractions will not be traced. VRAYforC4D tries to estimate the contribution of refractions to the image, and if it is below this threshold, these effects are not computed. Do not set this to 0.0 as it may cause excessively long render times in some cases.

Affect shadows – this will cause the material to cast transparent shadows, depending on the refraction color and the fog color. If it off shadows will be opak.

Affect Channels – Specifies which channels are going to be affected by the reflectivity of the material.

  • Color only – The reflectivity will affect only the RGB channel of the final render.
  • Color+alpha – Causes the material to transmit the alpha of the reflected objects, instead of displaying an opaque alpha.
  • All channels – All channels and render elements will be affected by the reflectivity of the material.

Trace Refractions – if this is off, refractions will not traced, even if the refraction color is greater than black.

Trace Depth – represents the maximum number of bounces that will be computed for refraction.

Use Exit Color – if this is on, and a ray has reached the maximum depth, the ray will be terminated and the exit color returned. When this is off, the ray will not be refracted, but will be continued without changes..

Reflect Exit Color – the color to be returned when the maximum ray depth has been reached but the reflection has not been computed completely. .

Refract Exit Color – the color to be returned when the maximum ray depth has been reached but the refraction has not been computed completely.

Use Despersion – this option enables the calculation of true light wavelenght dispersion.

Abbe – this option allows you to increase or decrease the dispersion effect. Lowering it widens the dispersion and vice versa.

Glossiness – controls the sharpness of refractions. A value of 1.0 means perfect glass-like refraction; lower values produce blurry or glossy refractions. Avalue 0 is a 100% rough lamber surface, you can control this material aspect with a shader or texture too.

Glossiness subdivs – control the quality of glossy refractions, adjust this to have more precise unsharp refraction, higher values give better result.

Texture – here an image texture or shader can be defined.

Mix Strength – defines the mixing proportion between the texture and color.

Invert – This option simply inverts the Texture Map, so transparent and solid areas are reversed. This works for both clipped images and images with built-in alpha channels.

Use Interpolation – these determine the options for the interpolation of glossy reflections. They are very similar to the options for the irradiance map. That it is not recommended to use interpolation for animations, since this may cause severe flickering.

Min rate – this value determines the resolution for the first interpolation pass. A value of 0 means the resolution will be the same as the resolution of the final rendered image, which will make the interpolation similar to the direct computation method. A value of -1 means the resolution will be half that of the final image and so on.

Max rate – this value determines the resolution of the last interpolation pass.

Color threshold  – this parameter controls how sensitive the interpolation algorithm is to changes in the color of reflections. Larger values mean less sensitivity and smaller values mean more sensitivity and better results.

Normal threshold  – this parameter controls how sensitive the algorithm is to changes in surface normals and small surface details. Larger values mean less sensitivity; smaller values mean more sensitivity to surface curvature and small details.

Samples – this is the number of samples that will be used to interpolate the blurry reflections at a given point. Larger values tend to blur the detail, although the result will be smoother. Smaller values produce results with more detail, but may produce blotchiness if the Subdivs parameter has been set too low.

Volume Fog Parameters

Enable Volume – if this is off, volume fog is disable.

IOR – index of refraction for the material, which describes the way light bends when crossing the material surface. A value of 1.0 means the light will not change direction.

Emission Color – this color controls the fog light emission (self-illumination).

Volume Color – the attenuation of light as it passes through the material. This option allows to simulate the fact that thick objects look less transparent than thin objects. Note that the effect of the fog color depends on the absolute size of the objects and is therefore scene-dependent. The fog color also determines the look of the object when using translucency.

Texture – here an image texture or shader can be defined.

Amount – the strength of the fog effect. Smaller values reduce the effect of the fog, making the material more transparent. Larger values increase the fog effect, making the material more opaque. In more precise terms, this is the inverse of the distance at which a ray inside the object is attenuated with am amount equal to the Volume Color.

Distance Bias – this parameter allows to change the way the fog color is applied; by adjusting this parameter you can make thin parts of the object to appear more transparent than normal, or less transparent than normal.

SSS Parameters

SSS on – sub-surface scattering. Light is scattered within the volume of the material or beneath the surface. This is the more physical correct approach, but needs some time to render, for faster SSS you can use the c4d SSS shader in most cases.

Translucency Color – normally the color of the sub-surface scattering effect depends on the Fog color; this parameter allows you to additionally tint the SSS effect.

Texture – here an image texture or shader can be defined.

Subdivisions – controls the quality of sub-surface scattering. Lower values will render faster, but the result will be more noisy. Higher values take longer, but produce smoother results.

Light Multiplier – a multiplier for the translucent effect.

Thickness – this limits the rays that will be traced below the surface. This is useful if you do not want or don’t need to trace the whole sub-surface volume.

Scatter Coefficient – the amount of scattering inside the object. 0.0 means rays will be scattered in all directions; 1.0 means a ray cannot change its direction inside the sub-surface volume.

Scatter Direction – controls the direction of scattering for a ray. 0.0 means a ray can only go forward (away from the surface, inside the object); 0.5 means that a ray has an equal chance of going forward or backward; 1.0 means a ray will be scattered backward (towards the surface, to the outside of the object).

Scatter Levels – determinate the deepness of scattering light ( how often a ray gets scattered until termination). the higher the value the more often the light is scattered within the volume. Higher values need longer render time but give nicer SSS.

Environment Fog – this parameter allows to use an atmospheric effect that allows the simulation of participating media like fog, atmospheric dust and so.

For real SSS, you should have volume activated, and in most cases also some slight diffuse body and most of the time some glossy reflection.

For “architectural glass” you can deactivate volume and just use plain refraction, you can also use the c4d Fresnel in refraction, also almost all reflective Materials should be combined with reflection (sharp or glossy).

Example: The Refraction Color Parameter

This example demonstrates the effect of the Refraction color parameter to produce glass materials. For the images in this example, the material has a gray Diffuse color, white Reflection color, and the Fresnel option is turned on.

Refraction color = Black
(0, 0, 0)
no refraction

Refraction color = Light Gray
(192, 192, 192)

Refraction color = White
(255, 255, 255)

Example: The Fog Color Parameter

This example demonstrates the effect of the Fog color parameter. Notice how the thick areas of the object are darker in the two images on the right because of the light absorption of the fog.

Fog color = White
(255, 255, 255)
no light absorption

Fog color = Gray
(243, 243, 243)

Fog color = Green
(230, 243, 213)

Example: The Fog Multiplier Parameter

This example demonstrates the effect of the Fog multiplier parameter. Smaller values cause less light absorption because of the fog; while higher values increase the absorption effect.

Fog multiplier = 0.5

Fog multiplier = 1.0

Fog multiplier = 1.5

Example: The Refraction IOR Parameter

This example demonstrates the effect of the Refraction IOR parameter. Note how light bends more as the IOR deviates from 1.0. When the index of refraction (IOR) is 1.0, the render produces a transparent object. Note however, that in the case of transparent objects, it might be better to assign an opacity map to the material, rather than use refraction.

Refraction IOR = 0.8

Refraction IOR = 1.0

Refraction IOR = 1.3

Refraction IOR = 1.8

Example: The Refraction Glossiness Parameter

This example demonstrates the effect of the Refraction glossiness parameter. Note how lower  Refraction glossiness values blur the refractions and cause the material to appear as frosted glass.

Example: The Refraction Depth Parameter

This example demonstrates the effect of the Refraction depth parameter. Note how too low of a refraction depth produces incorrect results. Also, in the last two examples, note how areas with total internal reflection are also affected by the Reflection depth .

Refraction depth = 1
Reflection depth = 5

Refraction depth = 2
Reflection depth = 5

Refraction depth = 4
Reflection depth = 5

Refraction depth = 8
Reflection depth = 5

Refraction depth = 8
Reflection depth = 8

Example: The Refraction Exit Color Parameter

This example demonstrates the effect of the refraction  Exit color  parameter. This is mostly useful to show areas of deep refractions in the image, or for materials needing higher refraction depth. Note how the red areas are reduced when the  Reflection depth  and Refraction depth  are increased.

Refraction Exit color = Off
Reflection depth = 5
Refraction depth = 5

Refraction Exit color = On
Refraction Exit color = Red
(255, 0, 0)
Reflection depth is 5
Refraction depth is 5

Refraction Exit color = On
Reflection depth = 8
Refraction depth = 8

Example: Dispersion

This example demonstrates the Dispersion capabilities of the V-Ray material and the effect of the Abbe parameter.

Dispersion = Off

Dispersion = On
Abbe = 10

Dispersion = On
Abbe = 50